1. Technical Field
The present disclosure relates to a sensing device. More particularly, the present disclosure relates to a capacitive sensing device.
2. Description of Related Art
For high technology nowadays, user interfaces of more and more electronic products have already employed touch panels, such that demands for touch sensing devices have increasingly matured. Touch sensing devices have already become the basis of any kind of user interface, and replacing touch sensing interface with traditional keyboard interface undoubtedly makes the user interface become more intuitional and easier for use.
Moreover, one of ordinary skill in the art can use the touch sensing interface to substitute mechanical keys necessary in various applications such as access control, mobile phone, MP3 player, personal computer peripherals, remote controller, etc., and costs for manufacturing products can thus be saved.
For a conventional capacitive sensing device, it usually needs two or more than two oscillators cooperated with each other such that a sensed capacitance variation can be detected according to the difference between frequencies of signals generated by the oscillators, to further sense a user's touch.
However, the manner mentioned above not only needs two or more than two oscillators, but also requires that operational characteristics of the oscillators have to be very consistent, otherwise inaccuracy will be easily generated to cause detection errors. Furthermore, using multiple oscillators not only makes circuits more complicated but also occupies a large circuit area and results in increase of costs.